Electrical resistivity of CuCo solid solutions at low temperature

Abstract

Metastable CuCo solid solutions are produced by vapour condensation onto a substrate held at 5 K. Co solved in Cu causes a negative temperature coefficient of the electrical resistivity at low temperature (resistance anomaly). The resistance anomaly depends on the square of the Co concentration up to about 3 at% Co. This result agrees with the observation that single Co atoms have no localized magnetic moment in a non‐magnetic host but get a moment by interaction. Annealing the CuCo films to e.g. Ta = 390 K leads to clustering of the Co atoms. With the Co atoms in magnetic clusters, the resistance anomaly varies linearly with Co concentration. The residual resistivity as a function of Co concentration follows straight lines always and the slope of these lines decreases with annealing.

Low temperature anomaly of the electrical resistivity of SnMn

“…In other systems like AuCo [1,2] and CuCo [3] single atoms of the second component (here Co) do not show a localized magnetic moment. In this case the resistance anomaly varies quadratically with Co concentration [4,5].…”